Scaling
As stated, pick dumbbells that are relatively heavy for you yet still allow you to complete each round of thrusters in very few sets. This workout should be treated like a sprint, so run hard and try to avoid resting until it is over. Intermediate athletes can perform this workout as prescribed, just with lighter dumbbells. Newer athletes can reduce the reps and shorten the runs.

Beginner Option
For time, fast and heavy:
15 dumbbell thrusters
Run 200 meters
12 dumbbell thrusters
Run 200 meters
9 dumbbell thrusters
Run 200 meters

To learn more about Fast and Heavy click here